Prompt-release, fast-absorption and improved bioavailable formulations can be prepared according to different known techniques:
Complexes and composites based on cyclodextrins or other polymers, in which the active ingredient has been loaded through solubilisation in water or other organic solvents, co-grinding to dryness or in organic solvents and/or freeze-drying.
Micronisation and amorphisation processes of the active ingredient.
Emulsions, microemulsions (W/O, O/W), multiple emulsions (W/O/W). Salification processes, even extemporary, or solubilization of the active ingredient as such or in conventional liquid formulations such as syrups, drops, solutions, soft-gelatin capsules, effervescent forms.Organic solvents and/or cosolvents (such as dioxane, dimethylacetamide, dimethylsulfoxide, dimethyl isosorbide or binary or multiple systems consisting of diethylene glycol monoethyl ether with polyethylene glycols added with non-ionic surfactants.
All the above mentioned procedures suffer, however, from some drawbacks and disadvantages.
Complexes and composites based on cyclodextrins or other polymers require costly processes, which are often difficult to carry out and do not ensure complete complexation of the active ingredient; moreover the active ingredient to polymer ratio is often a limiting factor to the preparation of an easy-to-administer pharmaceutical form.
Micronisation processes do not always ensure significant increases in plasma levels, while increasing the apparent density/volumes and surface areas of the powders thus making the production of capsules, tablets and granulates troublesome.
Amorphisation processes, although improving the bioavailability of the drugs, induce recrystallization in the time and often also lower stability of the active ingredient, thus negatively affecting the quality of the medicament.
Emulsions and/or microemulsions, either simple or multiple, are often unstable and cannot carry pharmacologically active amounts of the medicament.
Salification and/or solubilization processes of conventional pharmaceutical forms sometime cannot improve the bioavailability of sparingly permeable and absorbable, or lipophilic, medicaments, due to reprecipitation of the active ingredient in the biological fluids, thus removing the advantage of a technological process aiming at dissolving the medicament in the pharmaceutical formulation.
Prompt-release, improved bioavailability formulations should ensure the standardization of the physical pharmaceutical state of the active ingredient, for fast release from the pharmaceutical form and to reduce any deviation from linear release.